Stihl Engine Torque Specs

Stihl publishes a "Tightening Torques" table in the dealer service manual for each powerhead, and the figures below are read straight out of those tables. Stihl specifies in newton-metres — the current MS 261 and MS 271 manuals print no imperial column at all — so the ft-lb and… Read the rest ›

in-lb values here are conversions, with Stihl's own N·m figure recorded alongside every row so you can check the arithmetic. Note that the spark plug on these saws is a 25 N·m fastener: substantially more than a Honda GX (18 N·m), and the reason a generic "2-stroke plugs are light, 6-7 ft-lb" rule of thumb is wrong on a Stihl.

Where these numbers come from. 37 published figures, 2 confirmed gaps, every source named. How we checked ›

Every value comes from a genuine Stihl dealer service manual "Tightening Torques" page, identified by the model named in the document footer. Those manuals were read on a third-party manuals aggregator rather than a stihl.com URL — Stihl does not publish service manuals to the open web, only owner's manuals, which contain no torque data at all. The content is manufacturer-grade and each row's sourceType says so; it also says the host is a re-host, because that distinction matters more than a tidy-looking link. Two documented gaps: the MS 170/MS 180, where no service manual with a torque table could be located and two secondhand figures contradict each other, and the FS 91. Both are recorded as rows rather than filled by carrying a figure over from a neighbouring model.

Stihl MS 210 / MS 230 / MS 250 Manufacturer-published

series MS 210, MS 230, MS 250 (document footer names all three)
From the Stihl service manual covering all three saws. More about this engine ›

The table prints kpm and N·m with no imperial column; ft-lb/in-lb below are converted. The predecessor 021/023/025 manual prints identical figures for the flywheel, spark plug, clutch carrier and cylinder, which is a useful consistency check on this whole lineage.

Fastener Torque Where it comes from
flywheel to crankshaftM8x1 collar nut 21 ft-lbHigh 28 N·m. Degrease the crankshaft taper and flywheel and mount them oil-free.
spark plugM14x1.25 18 ft-lbHigh 25 N·m. Well above the 18 N·m a Honda GX M14 plug takes — do not apply a generic light-touch 2-stroke figure here.
clutch carrierM12x1 37 ft-lbHigh 50 N·m. The highest torque on the saw.
guide bar mountingDG8x18 collar screw 12 ft-lbHigh 16 N·m. This is the collar screw Stihl specifies, not a generic "bar nut" figure.
decompression valveM12x1.5 10 ft-lbHigh 14 N·m.
cylinder to engine housing screwIS-DG5x24 spline screw 84 in-lb= 7 ft-lbHigh 9.5 N·m. On a 2-stroke the cylinder and head are one casting — this is not a cylinder-head-bolt torque and there is no head-bolt sequence.
mufflerM5 collar locknut 71 in-lb≈ 5.9 ft-lbHigh 8 N·m.
ignition module to housingIS-DG5x24 35 in-lb≈ 2.9 ft-lbHigh 4.0 N·m.
filter housing / carburetorM5 collar locknut 24 in-lb= 2 ft-lbHigh 2.7 N·m.
chain brake coverIS-M4x15 18 in-lb≈ 1.5 ft-lbHigh 2.0 N·m.
spiked bumperIS-DG5x16 33 in-lb≈ 2.8 ft-lbHigh 3.7 N·m.

Stihl MS 261 / MS 261 C Manufacturer-published

series MS 261, MS 261 C
From the Stihl service manual "Tightening Torques" pages. More about this engine ›

N·m only — this manual prints no imperial column. Note the cylinder is a documented two-stage tightening procedure, not a single figure.

Fastener Torque Where it comes from
flywheel to crankshaftM8x1 nut 21 ft-lbHigh 28.0 N·m. Manual note 5: degrease crankshaft and flywheel and mount oil-free.
spark plugM14x1.25 18 ft-lbHigh
25.0 N·m. Stihl's own owner-facing guidance for this saw says only to "tighten it down firmly" — the numeric spec exists solely in the… Why › service manual, and this is it.
clutch carrier to crankshaftM12x1 left-hand 37 ft-lbHigh 50.0 N·m. LEFT-HAND thread. A distinct fastener from the flywheel nut — do not use one figure for both.
collar stud for guide barM8 17 ft-lbHigh 23.0 N·m. 30.0 N·m (22 ft-lb) instead on the "BE" quick-tensioner variant — check which bar mount your saw has.
decompression valveM10x1 10 ft-lbHigh 14.0 N·m.
cylinder to crankcase screw, 1st stageM5x20 35 in-lb≈ 2.9 ft-lbHigh 4.0 N·m. First of two stages — do not stop here.
cylinder to crankcase screw, 2nd stageM5x20 89 in-lb≈ 7.4 ft-lbHigh 10.0 N·m. Final figure, applied after the 4.0 N·m first pass.
muffler to crankcaseM5x16 89 in-lb≈ 7.4 ft-lbHigh 10.0 N·m.
muffler to cylinderM5x16 89 in-lb≈ 7.4 ft-lbHigh 10.0 N·m.
ignition module to crankcaseM4x20 35 in-lb≈ 2.9 ft-lbHigh 4.0 N·m.
spark arresting screen to mufflerM4x9.6 9 in-lb≈ 0.8 ft-lbHigh 1.0 N·m. The lowest figure on the saw — this is a screwdriver-feel fastener, and no ft-lb wrench will read it.

Stihl MS 271 C / MS 291 C Manufacturer-published

series MS 271 C, MS 291 C (ErgoStart trim)
From the Stihl service manual "Tightening Torques" pages. More about this engine ›

The document footer names only the "C" (ErgoStart) trim. The core engine fasteners are very unlikely to differ on a plain MS 271/MS 291 — ErgoStart changes the starter, not the crankcase — but this manual does not say so, so treat use on a non-C saw as informed inference rather than a confirmed spec.

Fastener Torque Where it comes from
flywheel to crankshaftM8x1 nut 21 ft-lbHigh 28.0 N·m. Identical to the MS 261.
spark plug to cylinderM14x1.25 18 ft-lbHigh 25.0 N·m.
clutch carrier to crankshaftM12x1 left-hand 37 ft-lbHigh 50.0 N·m. LEFT-HAND thread.
collar stud for guide barM8 / M10 12 ft-lbHigh
16.0 N·m; 30.0 N·m (22 ft-lb) on the plain collar screw and bushing variant. Why › Lower than the MS 261's 23 N·m for the same job — this figure does not carry across Stihl models.
cylinder to engine pan screwD6x50 and D6x35 97 in-lb≈ 8.1 ft-lbHigh 11.0 N·m. Same figure for both screw lengths.
muffler to cylinderD5x18 80 in-lb≈ 6.7 ft-lbHigh 9.0 N·m.
ignition module to engine panD4x18 35 in-lb≈ 2.9 ft-lbHigh 4.0 N·m.

Stihl FS 45 trimmer Manufacturer-published

series FS 45 (4140 powerhead family — see notes for read-across)
From the Stihl FS 45 service manual "Tightening Torques" page, which unusually prints lbf-ft alongside N·m — the imperial figures below are… More about this engine ›

Stihl's own, not conversions. This is the 4140-series powerhead, which multiple listings describe as shared with the FS 46, FS 55, FC 55, HL 45 and KM 55; the document itself only self-identifies as FS 45, so applying it to those models is informed inference rather than a confirmed spec.

Fastener Torque Where it comes from
spark plugM14x1.25 15 ft-lbHigh 20.0 N·m, printed by Stihl as 15.0 lbf-ft. Lower than the chainsaw powerheads' 25 N·m for the same thread — a trimmer figure is not a saw figure.
clutch carrier3/8" 12.5 ft-lbHigh 17.0 N·m, printed by Stihl as 12.5 lbf-ft.
starter cupM8 12.5 ft-lbHigh 17.0 N·m, printed by Stihl as 12.5 lbf-ft.
stub to mufflerM14x1.25 11 ft-lbHigh 15.0 N·m, printed by Stihl as 11.0 lbf-ft. Install with sealant.
muffler to cylinderIS-DG5x60 spline 80 in-lb≈ 6.7 ft-lbHigh 9.0 N·m, printed by Stihl as 6.6 lbf-ft.
engine pan / crankcase / cylinderIS-DG5x60 80 in-lb≈ 6.7 ft-lbHigh 9.0 N·m, printed by Stihl as 6.6 lbf-ft.
ignition module to cylinderIS-DG4x20 40 in-lb≈ 3.3 ft-lbHigh 4.5 N·m, printed by Stihl as 3.3 lbf-ft.
clutch drum to crankshaftpan head 8-32 35 in-lb≈ 2.9 ft-lbHigh 4.0 N·m, printed by Stihl as 3.0 lbf-ft. Shown here in in-lb because 3 ft-lb is below the usable range of a 3/8" ft-lb wrench.

Stihl MS 170 / MS 180

series MS 170, MS 180, MS 170 C, MS 180 C
Stihl's most popular homeowner saws, and the one model family on this page with NO usable published torque data. More about this engine ›

Stihl puts these specs only in the dealer service manual, and unlike the MS 210/261/271 manuals no MS 170/180 service manual with a "Tightening Torques" page could be located. The owner's manuals on stihlusa.com contain no torque figures at all — they refer anything past bar, chain and air-filter maintenance to a dealer.

No published torque figures for this engine. Every source we checked is under “What we found” below.
2 specs not published — flywheel to crankshaft, spark plug What we found ›
  • flywheel to crankshaftGAP: not published in any Stihl document that could be located. Two secondhand figures circulate and they contradict each other — one search synthesis cites 40 N·m (29.5 ft-lb), a forum post cites 20.2 ft-lb (27.4 N·m) attributed to a service-manual page. Neither was confirmed against a primary document, and they are 47% apart, so neither is presented as a value. The MS 210/230/250 figure (28 N·m) is a different, larger saw and is NOT offered as a substitute.
  • spark plugGAP: no Stihl-published figure located for these saws. Worth knowing what NOT to assume: every Stihl chainsaw powerhead with a published table (MS 210/230/250, MS 261, MS 271/291) specifies 25 N·m / 18 ft-lb on an M14x1.25 plug, and the FS 45 trimmer 20 N·m. A "2-stroke plugs are light, around 6-7 ft-lb" rule of thumb is roughly a third of every figure Stihl actually prints.

What is the spark plug torque on a Stihl chainsaw?

Every Stihl chainsaw powerhead with a published service-manual figure specifies 25 N·m (18 ft-lb) on its M14x1.25 plug — the MS 210, MS 230 and MS 250, the MS 261, and the MS 271 C and MS 291 C all print the same number. The FS 45 trimmer powerhead is lower at 20 N·m (15 lbf-ft, Stihl's own imperial figure). Be careful with generic advice here: "2-stroke spark plugs are light, 6-7 ft-lb" is a widely repeated rule of thumb and it is about a third of what Stihl actually specifies. Torque cold, on a clean plug seat.

What is the flywheel nut torque on a Stihl MS 250 or MS 261?

28 N·m (about 21 ft-lb) on the M8x1 collar nut, and the figure is identical across the MS 210/230/250, the MS 261 and the MS 271 C/291 C — Stihl has used the same spec across this whole class. Two details from the manual matter as much as the number: degrease the crankshaft taper and the flywheel and assemble them oil-free, and use a flywheel holding tool. A 2-stroke has no compression stroke to brake against, so there is nothing to stop the crank turning while you tighten.

Is the Stihl clutch a left-hand thread?

Yes on the clutch carrier — Stihl's tables list it as M12x1 L, and it loosens clockwise. It is also the highest-torque fastener on the saw at 50 N·m (about 37 ft-lb), which is a nasty combination: leaning hard on it in the wrong direction is exactly how the carrier or the crankshaft threads get ruined. Confirm the direction before applying force, and note the clutch carrier is a different fastener from the flywheel nut, with roughly double its torque.

What torque do the guide bar nuts take on a Stihl?

Stihl specifies the bar mount as a collar screw or collar stud rather than a generic "bar nut", and the figure genuinely varies by model: 16 N·m (12 ft-lb) on the MS 210/230/250 DG8x18 collar screw, 23 N·m (17 ft-lb) on the MS 261 M8 collar stud — or 30 N·m on its "BE" quick-tensioner variant — and 16 N·m on the MS 271 C/291 C, with 30 N·m for the plain collar screw and bushing version. There is no single Stihl bar torque to memorise; match the row to your saw and check which bar mount it has.

Why is there no torque data here for the Stihl MS 170 or MS 180?

Because Stihl does not publish it anywhere freely available. These specs live in the dealer service manual, and while the MS 210, MS 261 and MS 271 service manuals are findable, no MS 170/180 equivalent with a "Tightening Torques" page turned up; the owner's manuals contain no torque figures at all. Two secondhand numbers circulate for the flywheel nut and they are 47% apart, so this page records the gap instead of picking one. It also does not quietly substitute the MS 210/230/250 figure — that is a larger saw, and cross-applying specs between Stihl model families is exactly the error this page exists to prevent.

Are these figures in newton-metres or foot-pounds?

Stihl specifies in newton-metres. The current MS 261 and MS 271 service manuals print no imperial column at all, and the MS 210/230/250 table prints kpm and N·m only, so the ft-lb and in-lb values on this page are conversions from Stihl's N·m figure, which is recorded in the notes on every row so you can check the arithmetic. The one exception is the FS 45, whose manual does print lbf-ft alongside N·m — those imperial figures are Stihl's own. Anything under about 7 ft-lb is shown in in-lb, because that is below where a 3/8" ft-lb click wrench can be trusted.

Related lookups

Loading interactive lookup…